Trāde'-wind, n.

n. A wind in the torrid zone, and often a little beyond it, which blows from the same quarter throughout the year, unless when affected by local causes; — so called because of great advantage to navigators, and hence to trade. ☞ The general direction of the trade-winds is from N. E. to S. W. on the north side of the equator, and from S. E. to N. W. on the south side of the equator. They are produced by the joint effect of the rotation of the earth and the movement of the air from the polar toward the equatorial regions, to supply the vacancy caused by heating, rarefaction, and consequent ascent of the air in the latter regions. They are principally limited to two belts in the tropical regions, one on each side of the equator, and separated by a belt which is characterized by calms or variable weather.